Deep Brain Stimulation for Movement Disorders
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Deep Brain Stimulation for Movement Disorders Overview Deep brain stimulation (DBS) is a surgical procedure to implant a pacemaker-like device that sends electrical signals to brain areas responsible for body movement. Electrodes are placed deep in the brain and are connected to a stimulator/battery device. Similar to a heart pacemaker, a neurostimulator uses electric pulses to help regulate brain activity. DBS can help reduce the symptoms of tremor, slowness of movement, stiffness, and walking problems caused by movement disorders. It may be a treatment option for people who have Parkinson’s disease, dystonia, or essential tremor and whose symptoms are not well controlled with medication. Successful DBS allows people to better manage their symptoms, reduce their medications, and improve their quality of life. What is deep brain stimulation? In deep brain stimulation, electrodes are placed in a specific area of the brain (usually the subthalamic nucleus) depending on the symptoms being treated. The electrodes are placed on both the left and right sides of the brain through small holes made at the top of the skull. The electrodes are connected by long extension wires that are passed Figure 1. Overview of a deep brain stimulator (DBS). under the skin and down the neck to a battery- Electrodes are placed deep within the brain through small holes in the skull. The electrodes are connected by an powered stimulator under the skin of the chest (Fig. extension wire to a battery-powered stimulator placed 1). When turned on, the stimulator sends electrical under the skin of the chest. Because the left side of the pulses to block the faulty nerve signals causing brain controls the right side of the body and vice versa, tremors, rigidity, and other symptoms. DBS is commonly performed on both sides of the brain. A deep brain stimulator system has three parts that are implanted inside the body: The patient uses a handheld controller to turn the DBS system on and off. The doctor programs the • Neurostimulator – a programmable battery- stimulator settings with a wireless device. The powered pacemaker device that creates electric stimulation settings can be adjusted as a patient’s pulses. It is placed under the skin of the chest condition changes over time. Unlike other surgeries, below the collarbone or in the abdomen. such as pallidotomy or thalamotomy, DBS does not • Lead – a coated wire with a number of damage the brain tissue. Thus, if better treatments electrodes at the tip that deliver electric pulses develop in the future, the DBS procedure can be to the brain tissue. It is placed inside the brain reversed. and connects to an extension wire through a small hole in the skull. DBS is very effective at reducing dyskinesias, the uncontrolled wiggling movements caused by high • Extension – an insulated wire that connects the lead to the neurostimulator. It is placed doses of levadopa medication. Typically, DBS will under the skin and runs from scalp, behind the help make your symptoms less severe so that lower ear, down the neck, and to the chest. medication doses may be used. > 1 Electro des can be placed in the following brain areas (Fig 2): • Subthalamic nucleus (STN) – effective for tremor, slowness, rigidity, dystonia and dyskinesia. Most commonly used to treat Parkinson’s disease. • Thalamus (VIM) – effective for tremor. It is often used to treat essential tremor. • Globus pallidus (GPi) – effective for tremor, slowness, rigidity, dystonia and dyskinesia. It is used to treat dystonia and Parkinson’s disease. Who is a candidate? You may be a candidate for DBS if you have: • a movement disorder with debilitating symptoms (tremor, stiffness) and your medications have begun to lose effectiveness. • troubling “off” periods when your medication wears off before the next dose can be taken. • troubling “on” periods when you develop Figure 2. A cross section of the brain. Normal muscle medication-induced dyskinesias (excessive tone, movement, timing, and coordination depend on wiggling of the torso, head, and/or limbs). complex electrical circuits or feedback loops in the brain. The basal ganglia are responsible for activating and DBS may not be an option if you have severe inhibiting these feedback loops. untreated depression, advanced dementia, or if you In Parkinson’s disease, parts of the basal ganglia are have symptoms that are not typical for Parkinson’s either under- or over-stimulated. Normal movement is disease. replaced by tremor, rigidity and stiffness. DBS of specific ganglia alters the abnormal electrical circuits and helps DBS can help treat many of the symptoms caused stabilize the feedback loops, thus reducing symptoms. by the following movement disorders: with multiple physicians, nurses, and surgeons. The • Parkinson’s disease: tremor, rigidity, and team discusses the best treatment plan for each slowness of movement caused by the death of patient. If the team agrees that you are a good dopamine-producing nerve cells responsible for candidate for DBS, you will be contacted to relaying messages that control body movement. schedule an appointment with a neurosurgeon. • Essential tremor: involuntary rhythmic tremors of the hands and arms, occurring both at rest and during purposeful movement. Also Who performs the procedure? may affect the head in a “no-no” motion. Deep brain stimulation surgery is performed by a • Dystonia: involuntary movements and neurosurgeon who has specialized training in prolonged muscle contraction, resulting in functional neurosurgery. The surgical team also twisting or writhing body motions, tremor, and includes a neurologist. abnormal posture. May involve the entire body, or only an isolated area. Spasms can often be The surgical decision suppressed by “sensory tricks,” such as Seek treatment at a medical center that offers a touching the face, eyebrows, or hands. team approach and the full range of treatment options including medication, surgery, and A team of specialists including a neurologist, rehabilitation (physical, exercise, voice, balance). neuropsychologist, and neurosurgeon will evaluate your condition to determine if surgery is an option. The timing of when to consider DBS surgery is Your thinking and memory, current medications, different for each patient. If you have severe motor and general health will be evaluated. You will be disability despite optimal medications, then surgery videotaped performing a variety of movements should be considered. DBS should not be thought of (walking, finger tap, rising from a chair) while on as a last resort. As Parkinson’s disease progresses, and off medication. Your symptoms and abilities are DBS is no longer an option if your symptoms don’t measured using the Unified Parkinson Disease respond to medication, or if you are severely Rating Scale (UPDRS). disabled even in the best “on” state. And unlike other surgeries (pallidotomy, thalamotomy) that After your evaluation and videotaping is complete, damage brain tissue, DBS is reversible and can be your case will be discussed at a monthly conference turned off or removed if necessary. > 2 The surgery is performed in two stages. Stage 1 is implantation of the electrodes in the brain. About one week later, Stage 2 is performed. This includes implantation of the stimulator device in the chest and tunneling of the wires to the neck. What happens before surgery? You will typically undergo tests (e.g., blood test, electrocardiogram, chest X-ray) several days before surgery. An MRI scan of your brain will be performed. In the doctors office you will sign consent forms and complete paperwork to inform the surgeon about your medical history, including allergies, medicines, anesthesia reactions, and previous surgeries. Stop taking all non-steroidal anti-inflammatory medicines (Naprosyn, Advil, Motrin, Nuprin, Aleve, etc.) 1 week before surgery. Stop smoking, chewing tobacco, and drinking alcohol 1 week before and 2 weeks after surgery because these Figure 3. A stereotactic frame is attached to the activities can cause bleeding problems. You may patient’s head with four pins. also need to have clearance from your primary care physician or cardiologist if you have a history of other medical or heart conditions. No food or drink, including your Parkinson’s medication, is permitted a fter midnight the night before surgery. Try to get a good night’s sleep. The DBS surgery involves multiple steps and lasts most of the day, during which you will be awake and off medication. Morning of surgery • Shower using antibacterial soap. Dress in freshly washed, loose-fitting clothing. • Wear flat-heeled shoes with closed backs. • If you have instructions to take regular medication the morning of surgery, do so with small sips of water. • Remove make-up, hairpins, contacts, body piercings, nail polish, etc. • Leave all valuables and jewelry at home (including wedding bands). • Bring a list of medications (prescriptions, over- the-counter, and herbal supplements) with dosages and the times of day usually taken. • Bring a list of allergies to medication or foods. Arrive at the hospital 2 hours before your scheduled Figure 4. A skin incision (dashed line) is made across the surgery time to complete the necessary paperwork top of the patient’s head. Two small burr holes (circles) and pre-procedure work-ups. An anesthesiologist are drilled in the skull to pass the electrode into the brain. will talk with you and explain the effects of anesthesia and its risks. An intravenous (IV) line will be placed in your arm. Step 1: attach stereotactic frame The procedure is performed stereotactically, which What happens during surgery? requires attaching a frame to your head. While you For stage 1, implanting the electrodes in the brain, are seated, the frame is temporarily positioned on the entire process lasts 5 to 7 hours. The surgery your head with Velcro straps. The four pin sites are generally lasts 3 to 4 hours. injected with local anesthesia to minimize discomfort.